I've recently started learning the passive form of verbs and noticed a few different usages of particles that have been giving me a lot of trouble and I wanted to clarify/confirm.
From what I've gathered from my book and this site, when を is used with the passive form of a verb it implies that a person (subject marked with は) was affected in some way by the individual acting out the verb (marked with に)。
僕は妹に日記を読まれました。
→ My sister read my diary and it has bothered me.僕は妹に部屋を掃除された。
→ My little sister cleaned my room.
From my understanding because 日記 and 部屋 are marked with を it adds the implication that the subject/topic of the sentence (僕) is the owner of the 日記 and 部屋 since he was affected by his little sister acting out the verb. Is this correct?
However, I have seen examples where the subject (marked with が) seems to be the object/undergoes the change carried out by the verb instead of being marked with を. (Both the subject and the direct object can undergo the change?)
日記が妹に読まれました。
→ The diary was read by my little sister.部屋が妹に掃除された。
→ The room has been cleaned by my little sister.
In example 3 and 4, from my understanding these examples imply that the diary was read by the sister and the room was cleaned by the sister (diary and room undergoing the change), However since these are NOT tagged with 僕は(or some other individual) it is not implied that these do not belong to someone else. I.E. The diary being read and the room being cleaned do NOT affect an unnamed individual. And because of this from my understanding sentence 3.) and 4.) would be essentially the same in meaning as 5.) and 6.), basically this is just another way of saying the same thing?
妹は日記を読みました。
→ My little sister read the diary.妹は部屋を掃除した。
→ My little sister cleaned the room.
Is this correct?
Finally there's no way that を in examples 1 and 2 can be replaced with が to make an equivalent sentence is there?
僕は妹に日記が読まれました。
→ My sister read my diary and it has bothered me.僕は妹に部屋が掃除された。
→ My little sister cleaned my room.
Do sentences 7 and 8 make any sense or are they unnatural and grammatically incorrect? Can が and を be used interchangeably at all in these types of sentences?